Method of making plastic file folder



Sept. 30, 1969 H. PORIS ETAL 3,470,290

METHOD OF MAKING PLASTIC FILE FOLDER Original Filed Sept. 15, 1965 2 Sheets-Sheet 1 I A ENTOR S HARRY PORIS Y GEORGE S. HENDRIE WILSON, SETTLE,BATCHELDER ATT'YS. 8 CRAIG Sept. 30, 1969 H. PORIS ETAL 3,470,290

METHOD OF MAKING PLASTIC FILE FOLDER Original Filed Sept. 15. 1965 2 Sheets-Sheet II 1/ II II II I II II II I II INVENTORS HARRY PORIS BY GEORGE S. HENDRIE WILSON,SETTLE,BATCHELDER ATT'YS. a CRAIG United States Patent 3,470,290 METHOD OF MAKING PLASTIC FILE FOLDER Harry Poris, New York, N.Y., and George S. Hendrie,

Grosse Pointe Farms, Mich., assignors to Macoid Industries, Inc., Detroit, Mich., a corporation of Michigan Original application Sept. 15, 1965, Ser. No. 487,564. Divided and this application Feb. 28, 1967, Ser. No. 619,397

Int. Cl. B29c 17/02; B29d 7/24 US. Cl. 264291 2 Claims ABSTRACT OF THE DISCLOSURE A method of making a file folder wherein at least one linear portion of a thin gauge sheet of non-oriented plastic material is longitudinally compressed and simultaneously transversely tensioned, to form a reduced-thickness longitudinal fold line. The combination of longitudinal compression and transverse tension biaxially orients the crease line while eliminating the possibility of local thickening of the sheet on either side of the crease line. The sheet is folded along the crease line to provide front and rear walls for a file holder.

This application is a division of copending application Ser. No. 487,564, now abandoned filed on Sept. 15, 1965, by Harry Poris and George S. Hendrie, and assigned to a common assignee.

The present invention relates generally to plastic file folders. In particular, it relates to a method of making plastic file folders and apparatus therefor.

Due to the necessity of keeping records and the like, the commercial demand for file folders, used for storage, is great. This demand is almost exclusively satisfied at the present time by use of paper file folders of the socalled manila or kraft types. Such paper file folders have captured the market primarily because they are relatively inexpensive. However, paper file folders of this type possess several limiting deficiencies. Storage of magnetic records, such as magnetic memory cards, in paper file folders, usually of the expandable accordian pleat type, accelerates magnetic deterioration. The absorption of moisture from the air by a paper folder causes loss of strength as well as an increase in folder thickness. This in turn causes greater susceptibility to wear and leads to reduced useful life. Paper file folders occupy a high percentage of filing cabinet space because a relatively large folder wall thickness is required in order to provide the front and rear walls of the folder with adequate rigidity to serve their intended purpose. Paper file folders provide relatively poor abrasive resistance and poor tear resitance. Repeated use of such folders tends to destroy needed Wall rigidity, and repeated opening and closing progressively weakens and ultimately will rupture such folders along the joint crease or creases between the walls. The walls of such folders tend to collapse and lose their shape when filled with relatively heavy contents.

The present invention proposes overcoming the above recited deficiencies to the prior art by provision of a novel plastic file folder and method and apparatus of making the same.

The presently preferred folder embodiment of this invention is made by moving a sheet of plastic of substantially uniform thickness through a pair of rollers having spaced corresponding male and female annular projections defining nips therebetween to stabilize and position that portion of the sheet to be subsequently folded. The fold portion of the final folder is provided by localized strips of the stabilized sheet portion between additional opposed projections to define a densified plastic crease, while simulice taneously applying lateral tension to the sheet to take up any slack between the creasing projections. After the creases have been formed in the plastic sheet, the sheet is cut into folder outlines and folded along the creases to make a finished file folder.

As one alternative, the crease pressing step may be separately performed either before or after the cutting step.

When compared with prior art paper file folders, any plastic folder produced in accordance with this invention produces improved rigidity with reduced folder thickness. The reduced folder thickness occupies less filing space, leaving more space for record storage. Greater resistance to magnetic deterioration, moisture absorption, abrasion and tearing also characterizes plastic file folders of this invention. Locally densifying and cold working the plastic at the junction between the walls of the folder is inexpensively achieved, and accommodates repeated opening and closing of the folder without significant changes in strength.

Accordingly, it is a primary object of this invention to provide a novel plastic file folder and method of and apparatus for making the same.

A further object is to provide a method of making a plastic file folder by longitudinally creasing a localized area of a moving sheet while simultaneously transversely tensioning the sheet to prevent a build-up of plastic material at the creasing location.

Another object is the provision of a plastic file folder which occupies less space than comparable prior art folders and which resists rather than contributes to magnetic deterioration of stored magnetic records.

An additional object is the provision of a method of making plastic file folders having improved strength at the crease juncture between the folder walls, allowing for repeated opening and closing without significant change in strength.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification.

On the drawings:

FIGURE 1 is a fragmentary side view in cross-section shown schematically, illustrating a flat sheet of plastic material being extruded;

FIGURE 2 is a fragmentary schematic plan view of the plastic sheet of FIGURE 1;

FIGURE 3 is a fragmentary schematic plan view of the sheet of plastic material of FIGURE 2 being slit into several strips;

FIGURE 4 is a front view of the sheet being compressed in-to crease lines by a pair of rollers;

FIGURE 5 is an enlarged view in cross-section illustrating the impression of the creases impressed upon the central portion of the sheet in the manner illustrated in FIGURE 4;

FIGURE 6 is a perspective view of a presently preferred plastic file folder embodiment of this invention;

FIGURE 7 is a perspective view of an expandable file folder embodiment of this invention equipped with enclosing heat sealed sides and a top flap;

'FIGURE 8 is a perspective view of a third plastic file folder embodiment of this invention having a heat sealed identification tab and heat sealed 'hanging arms appropriately attached to the file walls; and

FIGURE 9 is a front view in cross-section of the sheet after the creases have been impressed upon the central portion of it.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

As shown in the drawings:

Reference is now made to the drawings wherein like numerals are used to designate like parts throughout, and more particularly to FIGURES 1 through 5 which depict the manipulative method steps preferably utilized in forming plastic file folders in accordance with the present invention.

FIGURES 1 and 2 illustrate the steps of extruding a flat sheet of nonorientated plastic from a block 12 through a slot 14. For reasons of economics, polyethylene is preferred, though other plastics may be used. Conventional apparatus and processing systems may be used to form the sheet 10 which is generally of a thickness 15 on the order of about five to forty mils. The thickness 15 of five to twenty mils is most frequently utilized for the manufacturing of two-flap file folders with ten mils being preferred for such folders. The thickness 15 of sheet 10 may be on the order of forty mils thickness when the file folders to be manufactured are to be used in conjunction with hanging files. The sheet 10, following extrusion, may be stretched to remove wrinkles, if such occur, but normally is not stretched sufiiciently to orient the plastic material within the sheet. Any sheet width may be extruded, although the preferred width of the extrusion slot 14 is on the order of 50 to 56 inches.

Extrusion of a wide sheet accommodates slitting the sheet into a series of parallel extending strips 16 as schematically illustrated in FIGURE 3. Conventional commercially available slitting apparatus may be used to slit the sheet 10 into the less wide sheets of strips 16.

Method and apparatus for creasing each of the strips of plastic sheets 16 along predetermined lines is shown in FIGURE 4. The sheet 16 passes between a pair of rollers 18 and 20. The roller 18 is a cylinder rotating about an axis 19 and having annular male outwardly projecting ridges 22 circumferentially and concentrically arrayed around axis 19. The outer or exposed surface of each of these ridges 22 thus defines one-half of a circular torus having a cross-sectional shape that is semi-circular. The ridges or projections 22 are substantially equally spaced apart through a center-to-center distance 21.

The roller 20 is a cylinder rotating on an axis 23, parallel to the axis 19 of the roller 18. The roller 20 has annular female inwardly depressed recesses 24 circumferentially arrayed around its axis 23. Each of these recesses or depressions 24 corresponds to and registers accurately with one of the male ridges or projections 22. Each of the female recesses '24 has an exposed surface which is toroidal and which has a cross-sectional shape that is semi-circular. The cross-sectional shape of the torus of which a female depression 24 is a surface, has a slightly larger diameter than the cross-sectional shape of the torus of which an annular male projection 22 is a surface, and these tori have concentric surfaces in the plane of the axis of the rolls 18, 20, as viewed in FIG- URE 4. The female recesses 24 are separated by the same center-to-center distance 21 as are the male projections 22.

Midway between each of the female recesses or depressions 24, and opposing the cylindrical surface of the roller 18 midway between the male projections 22, are cylindrical portions 26 of the roller 20. These cylindrical portions 26 have a slightly greater radius than the radius of the rest of the cylinder 20. Thus, the distance between cylindrical portions 26 and the roller 18, designated as distance 25, is appreciably less than the distance 27 between other cylindrical portions of the roller 20 and the roller 18.

The distance 27 is slightly less than the thickness 15 of the strips 16 to provide a feeding nip. The distance is substantially less than the thickness 15 of the sheet 16.

The distance between a male projection 22 and an opposed female depression 24, designated distance 29, is somewhat greater than the distance 27.

When a sheet is passed between the rollers 18 and 20, the sheet isdeflected to a sinuous or corrugated configuration by the rolls, the male projections 22 act as stretching projections on the moving sheet of plastic 16, while the cylindrical portions 26 act as groove forming projections on the sheet. Between the groove forming projections 26, the sheet is in a slack condition, i.e. the sheet is not gripped by the rolls 18, 20. But any such slackness is simultaneously opposed by the stretching due to the projections 22 on roller 18. Simultaneously with this stretching, or applying tension to oppose any slaokness in the sheet 16, the groove forming projections depress the moving sheet of plastic into creases along predetermined lines.

FIGURES shows a cross-section of a sheet of plastic that has had several creases impressed upon it by the apparatus shownin FIGURE 4. Each of these creases has a thickness which is only several times a fraction of the original extruded thickness of the sheet of plastic. In a typical embodiment of this invention, the thickness of the creases in the plastic sheet maybe on the order of three mils, while the original extruded thickness of the sheet is on the order of ten mils in thickness.

As a preferred embodiment of this invention, the creases in the plastic sheets to be made into folders are impressed upon the sheet moving through the apparatus designated in FIGURE 4 simultaneous with the applying of a tension to overcome slackness of the sheet. In this manner, bidirectional stressing is applied to the sheet. This bidirectional stressing improves the strength characteristics of the plastic while preventing thickening of the plastic sheet near the creases to any substantial degree beyond the thickness of the originally extruded sheet. FIGURE 9 shows a cross-sectional view of the sheet after it has been creased :as described above. By bi-directional stressing the sheet while the creases are impressed upon it, the material displaced from the creased area of the sheet is pulled away from the crease, thus preventing a build-up or thickening of plastic near the crease, while maintaining a substantially uniform thickness in the sheet except for the reduced thickness where the crease is. In this manner, after the sheet has been creased, not only can it lie flat as illustrated in FIGURE 9, but it can be subsequently folded along the creases without causing bulges in the walls of the folder.

The sheet of plastic is cut into an outline conforming to the final folder configuration. This cutting step may be performed either before or after the creasing steps. After the sheet has been cut into folder outlines, and the sheet has been creased along predetermined lines, the creased and cut folder outlines are folded along the creases into a file folder. This folding is accomplished by utilization of commercially available folding equipment.

Referring to FIGURE 6, there is shown a typical folder embodiment made according to this invention. The dense transversely extending lines 30, 31 and 32 constitute lines of fold providing a juncture 33 intermediate front and rear walls 34 and 35 of the finished plastic file folder 36. The folder 36 is provided with an integral identification tab 37 which may be flame treated to allow printing to be registered thereon.

While the preferred mode of manufacturing has been described above, it to be appreciated that the steps so disclosed may be varied and supplemented in order to produce a plastic file folder of the type comprehended by the present invention. In addition to the creasing of the sheet either preceding or following the cutting of the plastic strips or sheets into folder configurations, the juncture 33, as shown in FIGURE 7, may be formed separately from walls 34 and 35, and subsequently made integral with the walls by heat sealing.

While plastic file folder '36 of FIGURE 6 is a presently preferred embodiment of this invention, other types of plastic file folders are intended to be included within the scope of the present invention. By way of example only, FIGURES 8 and 9 depict two additional embodiments of this invention.

Expandable file folder 50 of FIGURE 7 may be formed in essentially the same manner as the file folder 36 of FIGURE 6, but is provided with two pleats 52, rather than one at the bottom 53 of the file folder, and with a flap top "54, of any desired construction, which may be locked into position by a retainer 56. A folder 50 is equipped with accordianpleated sides 58 which are preferably heat sealed to front and rear Walls 60 and 62, respectively.

FIGURE 8 illustrates a hanging file 64 having a single bi-axially orientated crease 66 forming a juncture between front and rear walls 68 and 70. An identification tab 72, as well as hanger books 74, are preferably heat sealed in the appropriate illustrated positions to the walls 68 and 70. The identification tabs 72 may be flame treated to accommodate registration of printing thereon, if desired. The hanging hook 74 may be of any desired configuration iand may be of separate pieces individually attached at the upper corners of wall 68 as illustrated, or may be of one-piece construction extending across the full width of the distal edge of folder walls 68 and 70 in heat sealed relation.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, and all changes which come within the meaning and range of equivalency are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. In a method of making a file folder of polyolefin material, the steps of simultaneously (1) compressing a narrow band of the material continuously longitudinally of the web to locally substantially reduce the thickness of the sheet by displacing material laterally from the creasing location, and (2) tensioning the sheet transversely to either side of the reduction location to distribute displaced material on either side of the crease, the compression of the web orienting the material of the web longitudinally and the tensioning of the web orienting the material of the web transversely at the creasing location, and the tensioning of the sheet transversely redistributing the material so that the overall thickness of the sheet, with the exception of the crease, remains substantially constant.

2. A method as defined in claim 1, wherein steps (1) and (2) are simultaneously performed by passing the web between a pair of rolls having cooperative surface portions tightly confining and compressing the web only at the location of said crease and having other surface portions spaced on either side of said crease to (a) transversely tension the sheet, and (b) accommodate the transverse flow of polyolefin material from the location of said crease into the remainder of the sheet, thereby preventing any localized thickening of the sheet adjacent the location of said crease.

References Cited UNITED STATES PATENTS 1,971,667 8/1934 Weeks 264286 2,582,294 1/ 1952 Steiner 18-55 3,083,410 4/1963 McGlamery 18-48 3,104,937 9/1963 Wyckoff 18-48 3,320,225 5/1967 Bradbury 264-210 XR 3,350,492 10/1967 Grotenboar 264-320 3,383,449 5/1968 Muller 264-287 ROBERT F. WHITE, Primary Examiner O RICHARD R. KUCIA, Assistant Examiner US. Cl. X.R. 264-210, 289, 339 

